Monday, 2 July 2012
Skinfold Measurements
Making accurate skinfold measurements is more than simply pinching the skin somewhere around a particular area and measuring the thickness. There are precise sites on which the measurements are to be taken. A well-trained technician can obtain accurate results, unlike most others who aren't trained and experienced to take accurate enough results.
To take a skin-fold measurement, first determine the correct measurement site. Grab the skin with the thumb and forefinger about 0.5 inch from the measurement site following the natural fold of the skin. Lift the skin up from the muscle, apply the calipers and wait for 4 seconds before reading the calipers (Fat is compressible, so reading the scale before or after the 4-sec delay may affect the results)
Readings are usually taken from:
Triceps (Midpoint between top of shoulder and bottom of elbow)
Chest (Midpoint between armpit and nipple)
Abdominal (1inch left and 0.5inch down of belly button)
Supriliac (Top of hipbone, in line with belly button)
Thigh (Midpoint between knee and hip)
Formulas to calculate:
Females:
Body Density = 1.0994921 - 0.0009929*sum + 0.0000023*sum^2 - 0.0001392*age
(triceps, suprailiac, thigh skinfold measurements)
Males:
Body Density = 1.1093800 - 0.0008267*sum + 0.0000016*sum^2 - 0.0002574*age
(chest, abdominal, thigh skinfold measurements)
Using those measurements, we can estimate our body fats using two formulas:
Siri
Percent Fat = [(495 / Body Density) -450] * 100
Brozek
Percent Fat = [(4.570 / Body Density) - 4.142] * 100
These are not accurate though, as it assumes that the density of fat-free mass to remain constant. So the actual fat percentage is slightly higher then the measured percentage in the lean, muscular type and vice versa for the obese type.
Although we need training and experience, it isn’t very difficult to calculate and estimate our body fat. This also doesn’t require many equipment, except for the special skinfold measuring calipers. As long as we have those, we are able to roughly calculate our body fat anywhere and everywhere. It’s doesn’t cost a lot either.
Source: http://www-rohan.sdsu.edu/~ens304l/skinfold.htm
Darius Low, S308
Methods of measuring body composition - Shamus
The method of measuring body composition that I prefer is Near Infrared Interactance (NIR).
This method of assessing body fat is based on the principles of light absorbtion, reflectance, and near infrared spectroscopy. To estimate body composition, a computerized spectrophotometer that has a scan and probe are used. The probe is placed onto a selected body site such as the biceps; it emitts an infrared light which passes through both fat and muscle and is reflected back to the probe. Subject data such as height, weight, sex, age, frame size and activity level are taken into consideration. Density measurements are obtained and incorporated into the manufacturer's prediction equations. A digital read out including percentage body fat and lean tissue are displayed.
This method is not the most accurate, but it is cost efficient and convenient. Futrex 5000 (an example of NIR) underestimated body fat by more than 4% in subjects greater than 30% fat and overestimated body fat by 4% in subjects less than 8% fat.
Its advantages include safe, non-invasive, fast, and convenient. It is inexpensive, and only costs anywhere from 20 to 40 dollars. It is available at health clubs, weight loss centers, and medical practices offering weight loss programs.
Source : http://www2.gsu.edu/~wwwfit/bodycomp.html
This method of assessing body fat is based on the principles of light absorbtion, reflectance, and near infrared spectroscopy. To estimate body composition, a computerized spectrophotometer that has a scan and probe are used. The probe is placed onto a selected body site such as the biceps; it emitts an infrared light which passes through both fat and muscle and is reflected back to the probe. Subject data such as height, weight, sex, age, frame size and activity level are taken into consideration. Density measurements are obtained and incorporated into the manufacturer's prediction equations. A digital read out including percentage body fat and lean tissue are displayed.
This method is not the most accurate, but it is cost efficient and convenient. Futrex 5000 (an example of NIR) underestimated body fat by more than 4% in subjects greater than 30% fat and overestimated body fat by 4% in subjects less than 8% fat.
Its advantages include safe, non-invasive, fast, and convenient. It is inexpensive, and only costs anywhere from 20 to 40 dollars. It is available at health clubs, weight loss centers, and medical practices offering weight loss programs.
Source : http://www2.gsu.edu/~wwwfit/bodycomp.html
Sunday, 1 July 2012
Calculating Body Fat composition -Cherin (3-08)
Method: Measuring Skinfolds
It estimates the percentage of body fat by measuring skinfold thickness at specific locations on the body.
They are generally taken at specific parts of the right side of the body. It is done by pinching the skin at a particular area and pulling the fold away from the underlying muscle so only the skin and fat tissue is being held. Special skinfold calipers are then used to measure the skinfold thickness in millimeters. It is taken twice and then averaged.
These are the main areas that are measured:
-Triceps
-Pectoral
-Subscapula (Beneath the edge of the shoulder blade)
-Midaxilla (Midline of the side of the torso)
-Abdomen
-Suprailiac (Just above the iliac crest of the hip bone)
-Quadriceps
There are many formulas used to calculate body fat, below is one of the simplest:
For Females:
Body Density = 1.0994921 - (0.0009929 x sum) + (0.0000023 x sum) - (0.0001392 x age)
"sum" refers to the sum of triceps, suprailiac and thigh skinfold measurements.
For Males:
Body Density = 1.1093800 - (0.0008267 x sum) +( 0.0000016 x sum ) -( 0.0002574 x age)
"sum" refers to the sum of pectoral, abdominal and thigh skinfold measurements.
For Females:
Body Density = 1.0994921 - (0.0009929 x sum) + (0.0000023 x sum) - (0.0001392 x age)
"sum" refers to the sum of triceps, suprailiac and thigh skinfold measurements.
For Males:
Body Density = 1.1093800 - (0.0008267 x sum) +( 0.0000016 x sum ) -( 0.0002574 x age)
"sum" refers to the sum of pectoral, abdominal and thigh skinfold measurements.
Saturday, 30 June 2012
Body Composition - Casandra Ong
The Bioelectrical Impedance Analysis:
The bioelectric impedance device measures the resistance of the body tissues, through the flow of a small electrical signal. The person being measured should not be in contact with any insulators of electricity, with legs aparts and arms away from the body. Some BI machines require a pair of electrodes, that are worn on the hands and wrists, and another pair worn on ankles and foot. Other BI machines only require the person to stand on two foot plates.
As BI measures the resistance of the body tissues, the proportion of body fat can be calculated as the current flows more easily through the parts of the body that are composed mostly of water, such as blood, urine and muscle, than it does through bone, fat or air. It is also possible to predict how much body fat a person has by combining the BI results with other factors such as height, weight, gender, fitness level and age.
Preferred Method:
This method is portable, easily accessible, simple to perform and can be done at home with the required equipment.
The bioelectric impedance device measures the resistance of the body tissues, through the flow of a small electrical signal. The person being measured should not be in contact with any insulators of electricity, with legs aparts and arms away from the body. Some BI machines require a pair of electrodes, that are worn on the hands and wrists, and another pair worn on ankles and foot. Other BI machines only require the person to stand on two foot plates.
As BI measures the resistance of the body tissues, the proportion of body fat can be calculated as the current flows more easily through the parts of the body that are composed mostly of water, such as blood, urine and muscle, than it does through bone, fat or air. It is also possible to predict how much body fat a person has by combining the BI results with other factors such as height, weight, gender, fitness level and age.
Preferred Method:
This method is portable, easily accessible, simple to perform and can be done at home with the required equipment.
Body Impedance Analysis - Michelle Dapito
Why is this method my favourite?
It is very cheap and easy to find compared to other methods as this feature is common in many of today's at-home digital scales. Weight is calculated automatically along with body fat content in less than a minute. Also, no special training or skill is required for this method.
Bioelectrial Impedance Analysis (BIA) - Stacey
How it works:
BIA measures the impedance or resistance to the signal as it travels through the water that is found in muscle and fat. The more muscle a person has, the more water their body can hold. The greater the amount of water in a person's body, the easier it is for the current to pass through it. The more fat, the more resistance to the current.
Advantages:
- Easy to use
- Portable
- Relatively low cost
Disadvantages:
- Less accurate than those used clinically or in nutritional and medical practice
- Tend to under-read body fat percentage
Why is it my preferred method?
It is not very costly and very accessible. It provides a quick and much less invasive choice of assessing body composition as the subject is only required to expose only the back of the wrist and the hand and foot to get results. Compared to the hydrostatic underwater weighing method which is gold standard test, this test is much more accessible and cheaper as the hydrostatic underwater weighing method is rare and are mostly available to athletes and for scientific research.
BIA measures the impedance or resistance to the signal as it travels through the water that is found in muscle and fat. The more muscle a person has, the more water their body can hold. The greater the amount of water in a person's body, the easier it is for the current to pass through it. The more fat, the more resistance to the current.
Advantages:
- Easy to use
- Portable
- Relatively low cost
Disadvantages:
- Less accurate than those used clinically or in nutritional and medical practice
- Tend to under-read body fat percentage
Why is it my preferred method?
It is not very costly and very accessible. It provides a quick and much less invasive choice of assessing body composition as the subject is only required to expose only the back of the wrist and the hand and foot to get results. Compared to the hydrostatic underwater weighing method which is gold standard test, this test is much more accessible and cheaper as the hydrostatic underwater weighing method is rare and are mostly available to athletes and for scientific research.
Monday, 25 June 2012
Dual-Energy X-Ray Absorptiometry (DEXA) - Lee YuChong (S3-08)
Dual-Energy X-Ray Absorptiometry (DEXA)
It is an enhanced version of the x-ray, and is considered one of the best ways to measure body composition. It is a multi purpose machine that can also be used to check for bone density, which may lead to health risks.
http://www.youtube.com/watch?v=pSL8AbwVuK4&feature=related
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